Injuries are a major cause of death and disability among the elderly. The unintentional injury death rate for ages 75 and older is more than three times the national average for all ages. Despite the severity of the problem, and the implications for medical care costs as well as personal and family burdens in a rapidly growing population of older people, there have been no detailed, population-based analyses of injuries among the elderly requiring hospital admission. Computer tapes of hospital discharges in Maryland for 1979-1984 will be used in combination with denominator tapes based on the 1980 census to calculate rates of injury-related hospitalization by age, race, and sex and by median family income of the area. Rates will also be calculated of specific types of injuries. Outcome variables will be length of stay, hospital costs, discharges to long-term care facilities, and deaths. These will be analyzed in relation to demographic variables and type of injuries. The relationship between injury diagnoses and medical diagnoses will be described, with specific attention to infections, a particular threat to elderly patients. Preliminary research indicates that the number of hospital deaths among patients with injury diagnoses greatly exceeds the number for which death certificates state that the underlying cause of death was an injury (i.e., death attributed to falls and other external causes). Deaths on the hospital tapes will be compared to deaths in the state mortality file, to distinguish the characteristics of the two groups. Based on the mortality file, death rates will be calculated by cause and by demographic variables. Data for ten hospitals in the Baltimore area that provide E codes for hospital discharges will be analyzed by cause of injury. Similarly cause of injury will be studied for five rural hospitals that provide E codes. The science of injury epidemiology has much to offer to the study and prevention of injury in the elderly. By identifying high-risk groups, important causes of injury, the nature of the injuries, and conditions associated with fatal outcomes, the study has the potential to influence the allocation of resources and facilitate the establishment of preventive objectives.